Commuters watched in amazement as a classical music quartet boarded an early-morning Metro in full evening dress.

The ensemble then sat down and proceeded to give a performance complete with cello, French horn, violin and clarinet.

The musicians, from the Cobwebs Orchestra, are taking part in a short film to be shown at Newcastle's Discovery Museum.

About 200 people are involved in the project. Each was asked to play two or three notes for a musical score written by Andy Jackson, who does outreach work for the Northern Sinfonia.

The four musicians on the train, Greg Pullen, cello, Ben Armshaw, violin, Andrew Smith, clarinet, and Bridie Jackson, French horn, were filmed performing part of the piece. Director Anton Hecht said: "The musicians were filmed from South Gosforth to South Shields and performed for passengers on the way back, earning a round of applause."

But one commuter said: "Some people were a bit upset when they had to move.

"It's typical of the Metro not to explain what's going on."

A Nexus spokesman said: "We get dozens of requests to film on the Metro and as long as it doesn't disturb our passengers we're happy to oblige.

"In this case, we apologise if anyone was upset but we deliberately chose the first train of the day which isn't crowded so as to cause as little disturbance as possible."